40 BULLETIN 1032, V. S. DEPAKTMEXT OF AGRICULTURE, 



The spray gun. used in spraying McFarlin vines four times, gave 

 the next highest yield, but the third highest percentage of uninfested 

 fruit of this variety. 



The results of four applications with the Bordeaux type of nozzle 

 on the McFarlin variety ranked third in yield and second in per- 

 centage of uninfested McFarlin berries. 



Xo very definite conclusions based on yield can be drawn from the 

 experiments of sprajdng on the Howe variety on account of injury by 

 the fireworm on the plats in 1918 and frost in the spring of 1919. Of 

 the Howe plats receiving three applications, however, the one sprayed 

 with the Bordeaux type of nozzle resulted in the highest percentage 

 of fruit free from fireworm injury, that sprayed with the mist type 

 of nozzle was second, and that with the spray gun was third. 



Four applications with the spray gun on the Howe variety gave the 

 highest percentage of uninfested fruit of all the plats on which the 

 spra}' gun was used. 



Generally speaking, four applications gave better results than three. 



On bogs that can be reflowed, a complete covering of the vines with 

 water for not less than 48 hours during the middle or latter part of 

 May is recommended as a help in the control of the fireworm. Since 

 most of the bogs on the Pacific coast, however, are managed as dry 

 bogs, spraying with 40 per cent nicotine sulphate 1 to 800, with the 

 addition of fish-oil soap at the rate of 2 pounds to every 50 gallons, 

 is recommended as the most feasible method of control of the black- 

 head fireworm in that locality. 



Between 250 and 300 gallons of this material should be used per 

 acre. In making up the nicotine sulphate spray, the fish-oil soap 

 should be mixed Avith about half the quantit}^ of water and the re- 

 quired amount of nicotine sulphate added with the remainder of the 

 water to prevent the formation of a precipitate which decreases the 

 effectiveness of the spray soliition and which might also clog the 

 nozzles and possiblj^ injure the vines. This spra}- solution can be com- 

 bined with Bordeaux mixture or lime-sulphur in the usual propor- 

 tions, in which case the process of mixing is the same as though water 

 were used. No soap^ however^ sJwuld he added if the Tiiixture contains 

 lime-sulphur. The large eddy-chamber type of nozzle, throwing a 

 medium fine mist, at a pressure of about 200 pounds at the tank, should 

 be used ; other types of nozzles may not only give unsatisfactory re- 

 sults but may also injure the blossoms. The spray gun should be em- 

 i^loyed only on lightly infested bogs. 



Vines which are lightly infested should have tlu'ee applications of 

 the nicotine sulphate spray, the first one when the new upright growth 

 has reached a length of about three-fourths of an inch, the second 

 when the blossoms are in the early " hook stage,'' and the third when 

 the vines are in full bloom. 



